System for forming SiC crystals having spatially uniform doping impurities

Abstract

A physical vapor transport system includes a growth chamber charged with source material and a seed crystal in spaced relation, and at least one capsule having at least one capillary extending between an interior thereof and an exterior thereof, wherein the interior of the capsule is charged with a dopant. Each capsule is installed in the growth chamber. Through a growth reaction carried out in the growth chamber following installation of each capsule therein, a crystal is formed on the seed crystal using the source material, wherein the formed crystal is doped with the dopant.

1. A physical vapor transport growth system comprising, in combination:
 a growth chamber charged with source material and a seed crystal in spaced relation; 
 a first porous capsule having in addition to the pores thereof at least one calibrated capillary of predetermined dimensions extending between an interior thereof and an exterior thereof, wherein an interior of the first capsule is charged with a first dopant, each calibrated capillary is sized for controlled effusion of dopant at a temperature between 1900° C. and 2400° C., and an exterior of the first capsule is positioned on or in the source material in the growth chamber; and 
 at least one heating element operative for heating the interior of the charged growth chamber and the first capsule positioned therein to a desired reaction temperature whereupon the source material forms a crystal on the seed crystal and the formed crystal is doped with the first dopant via controlled effusion of the first dopant through the calibrated capillary in the first capsule. 
 
     
     
       2. The system of  claim 1 , further including a second porous capsule having in addition to the pores thereof at least one calibrated capillary of predetermined dimensions extending between an interior thereof and an exterior thereof, wherein:
 an interior of the second capsule is charged with a second dopant and an exterior of the second capsule is positioned on or in the source material in the growth chamber; and 
 in response to heating the interior of the charged growth chamber and the second capsule positioned therein to the desired reaction temperature, the formed crystal is doped with the second dopant via controlled effusion of the second dopant through the calibrated capillary in the second capsule. 
 
     
     
       3. The system of  claim 2 , wherein the first and second dopants are the same. 
     
     
       4. The system of  claim 1 , wherein either the growth chamber, the capsule, or both is made of a material that is not reactive with the source material or the dopant. 
     
     
       5. The system of  claim 4 , wherein the material forming the growth chamber and/or the capsule is graphite. 
     
     
       6. The system of  claim 1 , wherein the chemical form of the dopant is elemental, carbide, or silicide. 
     
     
       7. The system of  claim 1 , wherein the dopant includes at least one of the following: vanadium, aluminum, boron and phosphorus. 
     
     
       8. The system of  claim 1 , wherein the growth chamber is charged with the source material in a powder form. 
     
     
       9. The system of  claim 1 , wherein the source material includes SiC.